Methods for physical downlink control channel (PDCCH) candidate determination

ABSTRACT

A wireless transmit/receive unit (WTRU) determines PDCCH candidates. For a slot, the WTRU determines a number of valid PDCCH candidates associated with at least one search space based on a number of designated search spaces associated with the WTRU in the slot, a type of the search space, a priority associated with the search space, a number of required CCE channel estimates associated with the search space, a maximum number of PDCCH candidates in a slot, and a number of control resource sets (CORESETs) associated with the slot. The WTRU may then attempt to decode CCEs in the at least one search space to recover a PDCCH associated with the WTRU. The WTRU may drop PDCCH candidates from the search space when the number of PDCCH exceeds a maximum value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage, under 35 U.S.C. § 371, ofInternational Application No. PCT/US2018/060894 filed Nov. 14, 2018,which claims the benefit of U.S. Provisional Application No. 62/585,992filed Nov. 14, 2017, and U.S. Provisional Application No. 62/615,787filed Jan. 10, 2018, which are incorporated by reference as if fully setforth.

BACKGROUND

A radio access network (RAN) is part of a mobile telecommunicationsystem providing wireless transmit receive units (WTRUs) with connectionto a core network (CN). In fifth generation (5G) or next generation (NG)wireless systems, the RAN may be referred to as New Radio (NR) or nextgeneration RAN. NR is designed to support great flexibility. Suchflexibility ensures that WTRUs with different capabilities can besimultaneously served with different types of traffic. The differentcapabilities for NR are varied and may be classified into extreme MobileBroadband (eMBB), Ultra High Reliable and Low Latency communications(URLLC), and massive Machine Type Communications (mMTC). In addition, NRneeds to support transmission in much higher frequency bands, such ascentimeter (cm)-wave and millimeter (mm)-wave frequencies. In order tosupport all of these capabilities and transmission methods, a WTRU mayneed to monitor a multitude of Physical Downlink Control Channel (PDCCH)candidates and determine when it is scheduled to receive a datatransmission. As such, the WTRU would need to check all possible PDCCHcandidates and this may necessarily increase blind detection complexity.Thus, it would be desirable to limit the blind detection complexity bydetermining which PDCCH candidates need to be monitored at any givenmoment.

SUMMARY

A wireless transmit/receive unit (WTRU) determines PDCCH candidates. Fora slot, the WTRU determines a number of valid PDCCH candidatesassociated with at least one search space based on a number ofdesignated search spaces associated with the WTRU in the slot, a type ofthe search space, a priority associated with the search space, a numberof required CCE channel estimates associated with the search space, amaximum number of PDCCH candidates in a slot, and a number of controlresource sets (CORESETs) associated with the slot. The WTRU may thenattempt to decode CCEs in the at least one search space to recover aPDCCH associated with the WTRU. The WTRU may drop PDCCH candidates fromthe search space when the number of PDCCH exceeds a maximum value.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawings,wherein like reference numerals in the figures indicate like elements,and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 10 is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 is a diagram illustrating an example Physical Downlink ControlChannel (PDCCH) candidate allocation among a variable number of controlresource sets (CORESETS) per slot;

FIG. 3 is a diagram illustrating an example PDCCH candidate allocationfor different discontinuous reception (DRX) states;

FIG. 4 is a method flow diagram showing an algorithm for dropping PDCCHcandidates from a search space; and

FIG. 5 is a method flow diagram showing one PDCCH candidatedetermination according to the embodiments described herein.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 102 a, 102 b, 102 c, 102 d, any of which may be referred to as a“station” and/or a “STA”, may be configured to transmit and/or receivewireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106/115, the Internet110, and/or the other networks 112. By way of example, the base stations114 a, 114 b may be a base transceiver station (BTS), a Node-B, an eNodeB, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller,an access point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., an eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit 139 toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WTRU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 10 is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 10 , the eNode-Bs160 a, 160 b, 160 c may communicate with one another over an X2interface.

The CN 106 shown in FIG. 10 may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a,184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-ab, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

To enable efficient use of the spectrum by a range of devices withvarying capability along with varying needs, control signaling has beenmade forward compatible in NR. For downlink (DL) or uplink (UL)scheduling, among other reasons, a WTRU may monitor PDCCH candidates ina search space located in a Control Resource Set (CORESET). A WTRU maybe configured with multiple CORESETs in a given carrier, for example, indifferent frequency portions of a carrier or in different symbols of aslot. A PDCCH candidate may be defined as a set of New Radio-ControlChannel Elements (NR-CCEs) which themselves are sets of NewRadio-Resource Element Groups (NR-REGs). An NR-REG may be defined as oneResource Block (RB) during one OFDM symbol or one radio frame. AnNR-PDCCH may be mapped contiguously or non-contiguously in frequency.The terms NR-PDCCH and PDCCH may be used interchangeably herein.

A WTRU may attempt to detect and decode (i.e. using blind detection)Downlink Control Information (DCI) intended for the WTRU in a PDCCHcandidate. A PDCCH candidate comprises a set of NR-CCEs. Such PDCCHcandidates may be located within a search space configured for aspecific WTRU. The search space may refer to the set of NR-CCE locationsin which the WTRU may find its PDCCHs. Search spaces may be common toall WTRUs in a cell or transmission/reception point (TRP), common to agroup of WTRUs in a cell/TRP or WTRU-specific. In turn, the searchspaces configured for the WTRU may be located in a plurality of controlresource sets (CORESETs) configured for a WTRU. The search spaces and/orCORESETs may be associated with a monitoring periodicity.

To ensure that a WTRU is capable of determining whether it has a DCI inany of its PDCCH candidates, there may be a limit to how many PDCCHcandidates that a WTRU may have to monitor at any given moment. Forexample, a WTRU may have a maximum number of PDCCH candidates in a slot.In another example, a WTRU may have a maximum number of NR-CCEs on whichall of the PDCCH candidates of a slot may be mapped to. The maximumnumber of NR-CCEs on which all of the PDCCH candidates of a slot may bemapped to may be a function of the CORESET-precoder-granularityparameter provided by higher layer signaling.

The set of PDCCH candidates may be associated with at least one of asearch space, CORSET, time element, aggregation level, DCI format,component carrier (CC) and/or bandwidth part (BWP). In a case where theset of PDCCH candidates is associated with the search space, the maximumnumber of PDCCH candidates may further depend on the search-space type(for example, common, group-common or WTRU-specific search space). In acase where the set of candidates is associated with a time element, theWTRU may monitor up to a maximum number of PDCCH candidates per symbol(or group thereof), or per slot (or group thereof), or per subframe (orgroup thereof), or per TTI. Such a time element may depend on thesubcarrier size (SCS) or may be defined with respect to a default SCS.In an example, a WTRU may monitor up to a maximum number of PDCCHcandidates per absolute time period.

Hereinafter, a set of PDCCH candidates associated with a singleparameter described above may be referred to as a group of PDCCHcandidates, and the parameters described above as grouping parameters.

A number of PDCCH candidates may be configured. A WTRU may be configuredwith a number of PDCCH candidates per group up to the maximum number ofPDCCH candidates. The maximum number of PDCCH candidates per group maydepend on a WTRU's capability or may be fixed or may be configurable.The configuration may be accomplished via a DCI, MAC Control Element(CE), and/or higher layer signaling. The configuration may beWTRU-specific, group-common, or common for all WTRUs. For a commonconfiguration, the maximum number of PDCCH candidates may be included insystem information.

In an embodiment, a WTRU may be configured to operate with less than amaximum number of PDCCH candidates per group. In such a case, the numberof PDCCH candidates per group may be configured via DCI, MAC CE, and/orhigher layer signaling. In one case, the number of PDCCH candidates pergroup is configured in a WTRU-specific manner.

The grouping parameter for which the maximum number of PDCCH candidatesapplies to may differ from the grouping parameter for which theWTRU-specific number of PDCCH candidates applies to. For example, amaximum number of PDCCH candidates may be applied to a slot, whereas aWTRU-specific number of PDCCH candidates may be configured per CORESET.As such, each of the n CORESETs located within a slot may have theWTRU-specific number of PDCCH candidates. The configuration of a(maximum) number of PDCCH candidates per group may be done explicitly,as described above. Alternatively, the configuration may be doneimplicitly via a function dependent on another WTRU configuration. Thefunction may depend on at least one of the number of CORESETsconfigured, number of search spaces configured, number of CCs configuredor activated, number of BWPs configured or activated, operating BW(possibly aggregated over all CCs and/or BWPs), or SCS. For example, thenumber of PDCCH candidates in a CC or BWP may depend on the SCS. Inanother example, the number of PDCCH candidates in a slot may depend onthe number of different SCS a WTRU may monitor in that slot. In anotherexample, the function for determining the number of PDCCH candidates maydepend on the number of CCEs to which the aggregate set of all PDCCHcandidates map to.

When configured with one or more values for a number of PDCCH candidatesper group, there may be situations where all of the values may notalign. For example, a WTRU may be configured with a number of PDCCHcandidates per slot of X and a number of PDCCH candidates per CORESET ofY. In a slot, there may be n CORESETs and it is possible that n times Yis greater than X (i.e. nY>X). In such a case, precedence and scaling isneeded.

The WTRU may receive a prioritized list of grouping parameters. In sucha case, the number of PDCCH candidates for a first group with thehighest priority may lead to scaling the actual number of PDCCHcandidates for a second group with lower priority. For example, thenumber of PDCCH candidates per slot may have the highest priority andany other number of PDCCH candidates may need to be scaled to ensurethat a WTRU need not monitor more PDCCH candidates per slot thanconfigured. In the example of CORESETs presented above, a WTRU may beconfigured with up to X PDCCH candidates per slot and up to Y PDCCHcandidates per CORESET. In the event of a situation where a WTRU has nCORESETs in a slot and n times Y is greater than X (i.e. nY>X), then theWTRU may scale the number of PDCCH candidates per CORESET.

In an embodiment where a WTRU is configured with a single value of PDCCHcandidates (i.e. for a single grouping parameter), the WTRU may thendistribute the PDCCH candidates over a set of other grouping parameters.For example, the WTRU may have a number of PDCCH candidates per slot andmay receive an explicit indication of how to spread the candidates overthe CORESETs present within a slot.

In an embodiment, the WTRU may implicitly determine the distribution ofPDCCH candidates based on a set of grouping parameters. It should benoted that the distribution need not be uniform. The distribution ofPDCCH candidates may be a function of at least one of time instance,time duration, number of monitored CORESETs in a time unit, number ofCORESET symbols, type of CORESETS in a time unit, Number of PRBs usedfor the CORESET, Periodicity of a CORESET within the slot, Number ofsearch spaces, Search Space Type, Aggregation level, Number of active orconfigured CCs, Number of active or configured BWPs, BW size of aBWP/CC/sum of BW of multiple (e.g. active) CCs/BWPs, SCS of a CC/BWP,DCI Type, Traffic type, and/or DRX state. In case where the distributionof PDCCH candidates is a function of the time instance, depending on theslot index, the WTRU may determine the number of PDCCH candidates. Incase where the distribution of PDCCH candidates is a function of thetime duration, depending on the slot duration, a WTRU may determine thenumber of PDCCH candidates. In case where the distribution of PDCCHcandidates is a function of the number of monitored CORESETs in a timeunit, the number of PDCCH candidates per CORESET may depend on thenumber of CORESETs in a slot. This may be per CC or BWP or in total overall CCs or BWPs. In case that the distribution of PDCCH candidates is afunction of the number of CORESET symbols, the number of symbols of aCORESET may determine the number of PDCCH candidates within thatCORESET.

When the distribution of PDCCH candidates is a function of the type ofCORESETs in a time unit, the number of PDCCH candidates per CORESET maydepend on a parameter of the CORESET and a parameter of other CORESETswithin a slot. In such a case, the parameter may be a quasi-co-location(QCL) to a reference signal. Thus, depending on the RS QCL with aCORESET and any other CORESET within a slot, the WTRU may determine thenumber of PDCCH candidates. This may enable allocating a differentnumber of PDCCH candidates per beam that a WTRU may be monitoring. Insuch a case, transmissions on a beam may be tied to a specific CORESETand depending on the number of beams that may be supported in a slot,the WTRU may determine a, possibly different, number of PDCCH candidatesper beam (i.e. per CORESET).

When the distribution of PDCCH candidates is a function of the number ofPRBs used for the CORESET, a CORESET spanning more PRBs may be allocatedwith more PDCCH candidates. When the distribution of PDCCH candidates isa function of the periodicity of a CORESET within the slot, a CORESETused for non-slot scheduling may be present in multiple instances withina slot. The number of instances may determine the number of PDCCHcandidates (e.g. per instance). When the distribution of PDCCHcandidates is a function of the number of search spaces, the number ofsearch spaces within a CORESET may determine the number of PDCCHcandidates within that CORESET. When the distribution of PDCCHcandidates is a function of the search Space Type, a common search spacemay have fewer candidates than a group common search space or than aWTRU-specific search space. When the distribution of PDCCH candidates isa function of the aggregation level, a search space may have onlycandidates of a subset of aggregation levels, and the subset maydetermine the number of PDCCH candidates. In case that the distributionof PDCCH candidates is a function of the number of active or configuredCCs, depending on the number of active CCs, each CC within a slot mayhave a subset of the total available PDCCH candidates. The distributionof PDCCH candidates within a CC may follow rules described herein.

When the distribution of PDCCH candidates is a function of the number ofactive or configured BWPs, depending on the number of active BWPs, eachBWP within a slot may have a subset of the total available PDCCHcandidates. The distribution of PDCCH candidates within a BWP may followrules described herein. When the distribution of PDCCH candidates is afunction of the BW size of a BWP or CC or sum of BW of multiple (e.g.active) CCs or BWPs, a larger CC may serve more WTRUs and to alleviatethe blocking probability, more PDCCH candidates may be allocated to theCC. When the distribution of PDCCH candidates is a function of the SCSof a CC or BWP, a larger SCS may lead to fewer PDCCH candidates assignedto the CC or BWP. In an example, a WTRU configured with multipleCCs/BWPs of different SCS may determine the total number of PDCCHcandidates per CC/BWP based on a reference SCS. In another example, aWTRU configured with multiple CCs/BWPs of different SCS may assume thePDCCH candidates are distributed in a manner that is a function of theSCS of each CC/BWP, and/or a function of the total set of SCSsconfigured for the WTRU.

When the distribution of PDCCH candidates is a function of the DCI Type,some DCI transmissions may be repeated (for example, repeated in a slotin one or more search spaces, in one or more CORESETs). This may enablean increase in PDCCH reception reliability. In such a case, thedetection of such a DCI may require a combination of multiple PDCCHblind detections. Therefore, supporting that DCI type may have an effecton the number of PDCCH candidates within a slot. When the distributionof PDCCH candidates is a function of the traffic type, a PDCCH candidatemay be associated with a traffic type. In an example, depending onwhether a slot, or CORESET or search space may be used for eMBB and/orURLLC may affect the number of PDCCH candidates associated with it. Whenthe distribution of PDCCH candidates is a function of the DRX state, theDRX state may affect the number of PDCCH candidates of a group or pergrouping parameter. For example, a DRX state may be tied to a limit ofthe number of PDCCH candidates of a specific aggregation level whileensuring a fixed number of PDCCH candidates of another aggregationlevel.

The distribution of PDCCH candidates may be a function of CCE mapping.For example, the total number of PDCCH candidates may depend on thetotal aggregate number of CCEs used for all the PDCCH candidates. Insuch a case, overlap of CCEs for different candidates, or candidatesusing fewer CCEs, may enable a higher number of total PDCCH candidates.

When a non-uniform allocation of PDCCH candidates over a set of groupingparameters exists, a priority may be assigned. For example, a CORESETmay have higher priority (for example, if it is associated with higherpriority transmissions) and may thus be allocated a larger amount ofPDCCH candidates than a CORESET associated with a lower priority. Inanother example, a search space within a CORESET may have higherpriority than another search space in the same CORESET and may thus beallocated more PDCCH candidates.

In an embodiment, a WTRU may be assigned a set of PDCCH candidatesassociated with a grouping parameter, but the WTRU may have to scaledown the number of PDCCH candidates (fro example, due to a collision ofmultiple grouping parameters within an allowable period). For example, aWTRU may be configured with a number of PDCCH candidates per searchspace as well as a maximum number of PDCCH candidates per slot. In theevent of multiple search spaces colliding in a slot, the WTRU may haveto scale down the number of PDCCH candidates in at least one of thesearch spaces. Each PDCCH candidate within a group may have an index.For the case where a WTRU may attempt blind detection on m PDCCHcandidates within a group, the m candidates with highest (or lowest)index may be used. The valid PDCCH candidates may be determined as afunction of at least one of: the size of the group, the value m, thecell (or TRP) ID, the WTRU ID, the SCS, the BWP ID, the CC ID, and/or afactor of the grouping parameter (for example, for a search spacegrouping parameter, the factor may be the aggregation level).

The WTRU may determine the maximum number of PDCCH candidates toaccommodate all of the groups of a first grouping parameter. Then with amaximum number of PDCCH candidates based on a second grouping parameter,the WTRU may use a pruning function to reduce the number of PDCCHcandidates in the groups associated with the first grouping parameter.For example, a WTRU may have n CORESETs in a slot, each CORESET may beconfigured with Y PDCCH candidates, however a slot may have a maximumnumber of X PDCCH candidates. If n times y is greater than X (i.e.nY>X), then the WTRU may use a pruning function to reduce the number ofcandidates for each CORESET.

In another example, a WTRU may be configured with n CORESETs in a slot.A CORESET may be configured with Y PDCCH candidates. A slot may have amaximum number of CCEs on which PDCCH candidates may be mapped. PDCCHcandidates may be mapped to such CCEs, (for example, where such maximumnumber of CCEs may be used to reduce channel estimation complexity). TheWTRU may use a pruning function to reduce the number of candidates forat least one CORESET if the sum of all CCEs used for the nY PDCCHcandidates exceeds a maximum configured value.

In another example, PDCCH candidates may be pruned to achieve both themaximum number of PDCCH candidate per slot and the maximum number ofCCEs used by the PDCCH candidates per slot. Such a pruning algorithm mayconsider all of the search spaces present in a slot and prune PDCCHcandidates from one or more such search space. The pruning algorithm maybe stopped when a remaining number of candidates is less than a maximumvalue. For example, the pruning algorithm may be stopped when the sum ofall PDCCH candidates that have not yet been pruned is equal to a certainvalue. Alternatively, the pruning algorithm may be stopped when thetotal number of required CCE estimates for the remaining PDCCHcandidates is less than the maximum value. Note that the stoppingcriteria may be modified as required while not affecting the details ofthe pruning function. In this example, a random cycling method is usedto remove some PDCCH candidates per group (in this case, per searchspace or per CORESET). Such a random cycling method may help reducePDCCH blocking probability by ensuring that the same candidates are notalways pruned in every slot.

A WTRU configured with multiple PDCCH monitoring occasions in a slot maydetermine a subset of PDCCH candidates m_(n) _(CI) per search space suchthat and

m_(n_(CI)) = 0, … , M_(p, n_(CI))^( ^(*)(L)) − 1${M_{p,n_{CI}}^{\,^{*}{(L)}} \leq {M_{p,n_{CI}}^{(L)}\mspace{14mu}{and}\mspace{14mu}{\sum\limits_{p \in P}M_{p,n_{CI}}^{\,^{*}{(L)}}}} \leq X},$where m_(n) _(CI) is a PDCCH candidate identifier, M_(p,n) _(CI) ^((L))is the maximum number of PDCCH candidates a WTRU is configured tomonitor for CORESET p and aggregation level L, and X is the maximumnumber of blind decoding attempts. The WTRU may further prune the numberof PDCCH candidates per search space such that the total number of CCEsfor all the PDCCH candidates within a slot is less than or equal to Y.The value of Y may depend on the CORESET-precoder-granularity. Forexample, the value of Y may correspond to, or be proportional to, aproduct between a maximum number of CCEs for which the same precoder maybe assumed Z and the CORESET-precoder-granularity (possibly divided by anumber of REGs per CCE, if CORESET-precoder-granularity is in units ofREGs). This approach ensures that the channel estimation effort to beundertaken by the WTRU remains within a reasonable limit. The sum of theCCEs used for all the PDCCH candidates may be quantized to determine thenumber of channel estimations required. Such a number may be determinedby the WTRU as a function of CCEs used for the PDCCH candidates and theCORESET-precoder-granularity.

The WTRU may prune the PDCCH candidates in a slot by first settingM*_(p,n) _(CI) ^((L))=M_(p,n) _(CL) ^((L)) for all monitored P and L,and then cycling through monitored P and L and reducing the value ofM*_(p,n) _(CL) ^((L)) by 1 at each iteration. The order of the cyclingis determined based on the following:i ₁=(n _(RNTI)·2¹⁴ +n _(s)·2⁹ +N _(ID) ^(cell))mod(|Q|)

p₀=q_(i) ₁i ₂=(n _(RNTI)·2¹⁴ +n _(s)·2⁹ +N _(ID) ^(cell))mod(|L|)

L₀=L_(i) ₂

For 1≤j≤|Q|−1

-   -   p_(j)=q_(i) ₁ _(+j),    -   For 1≤k≤|L|−1        -   L_(k)=L_(i) ₂ _(+k)

where Q={q₀, q₁, . . . q_(|Q|)} is the set of all monitored controlresource sets (i.e. Q is a subset of P).

At the end of each pruning step within each cycle, the WTRU maydetermine if both the X and Y criteria are achieved. If so, the pruningmay be terminated and the set of monitored PDCCH candidates may bedetermined.

Referring to FIG. 4 , a method 400 of the pruning algorithm describedherein is shown. The method 400 starts at step 410, where the order of aWTRU's search spaces are randomized and an index is assigned to eachsearch space. For the first indexed search space, step 420, adetermination is made whether the total number of PDCCH is above athreshold, step 430. Alternatively, step 430 may include determiningwhether a total number of CCE estimates is above a threshold. If thethreshold of step 430 is not exceed, in either case, the pruning processis stopped at step 440. If the threshold is exceed at step 430 (in otherwords, the total number of PDCCH candidates is above a threshold or thetotal number of CCE estimates is above a threshold), then at step 450 aPDCCH candidate is removed from the set of PDCCH candidates for theindexed search space. At step 460, the process advances to the nextindexed search space and step 430 is repeated.

To further randomize the pruning function, the elements in m_(n) _(CI)may first be randomized, possibly as a function of at least one of theWTRU ID, RNTI, slot number, cell ID, carrier ID, the SCS or the BWP ID.

In another example, the criterion related to the maximum number of CCEsto which all the PDCCH candidates may map, may have higher priority. Insuch a case, the order of pruning over aggregate level L may bedetermined to reduce candidates with greater CCE footprint first (e.g.the WTRU may prune candidates with higher aggregation level first).

FIG. 2 illustrates an example Physical Downlink Control Channel (PDCCH)candidate allocation among variable number of control resource sets(CORESETs) or search spaces per slot. In this example, a WTRU may beconfigured with a maximum number of PDCCH candidates per slot. The WTRUmay be configured with multiple CORESETs or search spaces each withdifferent monitoring occasions (possibly to enable slot and non-slotscheduling). The number of CORESETs or search space per slot may vary.For the case where there are n CORESETs or search spaces within a slot,the WTRU may assume each CORESET or search space has floor(X/n) PDCCHcandidates (assuming X PDCCH candidates per slot). Alternatively oradditionally, the number of PDCCH candidates per CORESET or search spacemay not be uniform and may depend on the CORESET or search space type(for example, based on the beam associated with the CORESET).

As shown in FIG. 2 , a WTRU may monitor a variable number of CORESETS orsearch spaces per slot (i.e. where the monitoring periodicity of eachCORESET or search space is different). In this example, the WTRU mayhave a fixed number of PDCCH candidates per slot. In such a case, thefixed number of PDCCH candidates per slot may need to be allocateddepending on the number of CORESETS or search space (and possibly thetype of CORESETS or search spaces) in a slot. In the example shown inFIG. 2 , there are a maximum of 44 PDCCH candidates per slot, configuredby way of one the methods described above. In slot n, the 44 PDCCHcandidates may be allocated such that a common search space (CSS) hasgreater priority than a UE specific search space (UESS 1), and UESS 1has greater priority than UESS 2. Thus, in the example, in slot n (andn+6), the WTRU determines that the total number of PDCCH candidates toaccommodate all monitored search spaces would exceed the maximum value.As such, the WTRU drops some (for exmaple, all) PDCCH candidates fromUESS2.

In other slots, such as in slot n+1 and in slot n+2, the total number ofPDCCH candidates to accommodate the monitored search spaces does notexceed the maximum value and as such the WTRU monitors all assignedPDCCH candidates. The exact number of PDCCH candidates per CORESET orsearch space may be determined as a function of priority level, totalnumber of PDCCH candidates to share, number of CORESET or search spaceTypes, maximum number of PDCCH candidate per CORESET search space (orper CORESET or search space Type) or the like as described above. Theselection of the PDCCH candidates within a CORESET or search space maydepend on the slot number, the WTRU ID, the CORESET or search spaceType, or any other parameter as described herein.

In an embodiment, a WTRU may be configured with a maximum number ofPDCCH candidates per carrier per slot (e.g. X). Furthermore, the WTRUmay be configured with a number of PDCCH candidates per CORESET (e.g.Y). For slots with n CORESETS, the number of PDCCH candidates perCORESET is Y as long as n times Y is less than or equal to X (i.e. nY≤X)otherwise it is floor(X/n).

In another embodiment, a WTRU may have a configured or fixed number ofPDCCH candidates per slot and be configured with multiple active BWPs inthe slot. The PDCCH candidate distribution may be a function of totalnumber of BWP, BWP index, BWP size and SCS of the BWP. For example, theX total PDCCH candidates may be split unevenly such that larger BWPshave more PDCCH candidates than smaller BWPs. Alternatively, theconfigured number of PDCCH candidate per slot may be per reference SCSslot size. Therefore, a BWP with larger SCS may have fewer PDCCHcandidates per its slot duration than another BWP with smaller SCS.

In another embodiment, a WTRU may have a configured or fixed number ofPDCCH candidates per slot and be configured with multiple CORESETs in aslot. The PDCCH candidates may be allocated, possibly in a uniformmanner, to the CORESETs present in a slot. The WTRU may also have a DRXpattern operating on sub-slot level. For example, in a DRX state, theWTRU may only monitor a subset of all CORESETs in a slot. In such case,the number of PDCCH candidates per CORESET may depend on the DRX state.

FIG. 3 illustrates an example PDCCH candidate allocation for differentdiscontinuous reception (DRX) states. As shown in FIG. 3 , a WTRU mayoperate with fixed number of PDCCH candidates per slot. In the exampleshown in FIG. 3 , there are 44 PDCCH candidates per slot. The WTRU mayoperate under different DRX states in each slot and each DRX state mayreduce the number of CORESETs (or search spaces) that a WTRU monitors ina given slot. In the example case shown in FIG. 3 , for slots in DRXstate 1, a WTRU has 4 CORESETs to monitor per slot and thus may assume11 PDCCH candidates per CORESET. The WTRU monitors 11 PDCCH candidatesper slot because there are 4 CORESETs, and thus allocates the 44 PDCCHcandidates equally amongst the 4 CORESETs. For slots in DRX state 2, theWTRU has 2 CORESETs to monitor per slot and may thus determine tomonitor 22 PDCCH candidates per CORESET. For slots in DRX state 3, someslots have a single CORESET and the WTRU may then determine to monitorall 44 PDCCH candidates in that CORESET. Other slots have zero CORESETsin this DRX state. However, given the constraint that there is a maximumof 44 PDCCH candidates per slot, the candidates may not be re-allocatedfrom a slot with no CORESETs to a slot with CORESETs. However, in thecase of multiple BWP or CC, it is possible that other BWP or CC may takeadvantage of the unused PDCCH candidates in those slots.

A WTRU may determine the number of PDCCH candidates as a function ofpreviously received DCI. A WTRU may detect and decode a first DCI thatmay affect the number of PDCCH candidates for an upcoming set ofresources. For example, a WTRU may detect and decode a first DCI for adata transmission in a slot, and the WTRU may then adjust the number ofPDCCH candidates that it may blindly detect for the duration of theslot.

In an embodiment, a WTRU may be configured for both slot and non-slotscheduling. The WTRU may detect a DCI in a first PDCCH candidatelocation for a transmission in a slot (possibly the same slot as thatwhich the DCI was transmitted in). The scheduled data transmission mayoverlap the transmission of other PDCCH candidates (for example, overlapin time). In such a case, the WTRU may reduce the number of PDCCHcandidates to blind detect thereby eliminating PDCCH candidates thatoverlap the previously scheduled transmission. This may reducecomplexities involved with simultaneous data reception and blinddetection of other PDCCH candidates. An example of this is where a WTRUis configured with multiple CORESETs in a slot, and in different timeinstances. The WTRU may detect and decode a DCI in a first CORESET for atransmission overlapping in time with a second CORESET. The WTRU mayattempt blind detection on a reduced number of PDCCH candidates of thesecond CORESET (for example, if the CORESET is in frequency resourcesorthogonal to the data transmission).

In an embodiment, a WTRU may be scheduled for a transmission in a subsetof symbols of a slot (possibly from a DCI transmitted in the same slotor transmitted in a previous slot). For any other PDCCH candidategrouping parameter in a slot with the scheduled transmission, the WTRUmay reduce the number of PDCCH candidates. For example, a WTRU isscheduled for a transmission on a first set of symbols in a slot, andthe WTRU is also configured with more CORESETs within the slot. In sucha case, the WTRU may reduce the number of PDCCH candidates in theremaining CORESETs of the slot. This may reduce complexities involvedwith simultaneous data processing and blind detection of other PDCCHcandidates.

In these examples, if each CORESET has up to Y PDCCH candidates, uponbeing scheduled in a first CORESET with a data transmission simultaneousto or in a same slot as the reception of the second CORESET, the WTRUmay attempt blind detection on Z PDCCH candidates in the second CORESET,where Z<Y. This example may be extended to the case where the first DCIschedules the WTRU over multiple slots (for example, using slotaggregation). In such a case, the WTRU may alter the number of PDCCHcandidates in the set of slots for which the scheduling assignment isvalid.

In an embodiment, a WTRU may detect and decode a DCI in a first PDCCHcandidate indicating a slot-based scheduling assignment. The WTRU maynot expect other DCI for non-slot based transmissions occurring withinthe slot of the scheduled assignment on that CC and/or BWP. The WTRU maythus increase the number of PDCCH candidates for non-slot basedscheduling on any CC and/or BWP where no slot based schedulingassignment is present.

The time between a DCI scheduling a transmission and the transmissionitself may also determine the number of other PDCCH candidates that aWTRU may attempt to blind detect, for that CC and/or BWP or for otherCCs and/or BWPs.

Referring to FIG. 5 , a method flow diagram 500 according to severalaspects described herein is shown. Beginning at step 510, a WTRUconsiders all of the search spaces to be monitored in a slot. The WTRUranks the search spaces by search space type, step 520. The WTRU rankssearch spaces within a search space type by configured priority order,step 530. The WTRU then selects a highest priority search space, step540. For the select search space, a determination is then made whetherthe total number of PDCCH is above a threshold, step 550. Alternatively,step 550 may include determining whether a total number of CCE estimatesis above a threshold. If the threshold of step 550 is exceeded, ineither case, at least one PDCCH candidate from the search space isdropped, step 560. In one scenario, all potential PDCCH candidates maybe dropped from the search space. If the threshold of step 550 is notexceeded, all remaining PDCCH candidates are kept in the search space,step 570. The next highest priority search space is selected, step 580,and the process repeats at step 550 using the sum of the PDCCHcandidates for the current search space under consideration and allpreviously kept PDCCH candidates for previously considered (i.e. higherpriority) search spaces

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method for use m a wireless transmit/receiveunit (WTRU), the method comprising: determining, for a slot, physicaldownlink control channel (PDCCH) candidates associated with one or moresearch spaces based on each of the following: a number of the one ormore search spaces associated with the WTRU for the slot, a type of theone or more search spaces, a priority associated with the one or moresearch spaces, and a maximum number of PDCCH candidates to be monitoredby the WTRU in the slot, wherein each of the one or more search spacesis associated with a respective control resource set (CORESET), and themaximum number of PDCCH candidates to be monitored by the WTRU in theslot depends on a subcarrier size (SCS); receiving a wireless signal inthe slot: and decoding at least one PDCCH transmission, wherein thePDCCH transmission corresponds to at least one of the PDCCH candidates,and wherein the PDCCH transmission is comprised in one or more controlchannel elements (CCEs) comprised in the wireless signal.
 2. The methodof claim 1, further comprising: dropping at least one PDCCH candidatefrom the PDCCH candidates associated with the one or more search spacesbased on a number of PDCCH candidates associated with the one or moresearch spaces exceeding the maximum number of PDCCH candidates to bemonitored by the WTRU in the slot.
 3. The method of claim 2, wherein thedropping of the at least one PDCCH candidate is based on at least onerule.
 4. The method of claim 2, wherein the dropping of the at least onePDCCH candidate is a function of a priority level associated with atleast one of the one or more search spaces.
 5. The method of claim 2,wherein the dropping of the at least one PDCCH candidate is based on atype of at least one of the one or more search spaces.
 6. The method ofclaim 2, wherein the dropping of the at least one PDCCH candidate isbased on a total number of search spaces monitored by the WTRU in theslot.
 7. The method of claim 2, further comprising: receiving a messagefrom a base station, wherein the message comprises informationindicating the maximum number of PDCCH candidates to be monitored by theWTRU in the slot.
 8. The method of claim 1, further comprising: droppingat least one PDCCH candidate from the PDCCH candidates associated withthe one or more search spaces based on a number of channel estimates tobe performed on CCEs of the PDCCH candidates associated with the one ormore search spaces exceeding a maximum value of channel estimates. 9.The method of claim 1, wherein at least one of the one or more searchspaces is configured such that PDCCH candidates associated with the atleast one of the one more search spaces are restricted to a subset ofaggregation levels.
 10. The method of claim 1, wherein each of the oneor more search spaces is associated with a configured monitoringperiodicity.
 11. The method of claim 1, wherein the WTRU is configuredwith a respective number of PDCCH candidates per search space for eachof the one or more search spaces, the method further comprising: scalinga number of PDCCH candidates in at least one of the one or more searchspaces based on a total number of configured PDCCH candidates in theslot for all of the one or more search spaces exceeding the maximumnumber of PDCCH candidates to be monitored by the WTRU in the slot. 12.The method of claim 11, wherein scaling the number of PDCCH candidatesin at least one of the one or more search spaces comprises dropping allof the PDCCH candidates in the slot for the at least one of the one ormore search spaces.
 13. A wireless transmit/receive unit (WTRU)comprising: a processor configured to determine, for a slot, physicaldownlink control channel (PDCCH) candidates associated with one or moresearch spaces, wherein the determination is based on each of thefollowing: a number of the one or more search spaces that are associatedwith the WTRU for the slot, a type of the search space, a priorityassociated with the one or more search spaces, and a maximum number ofPDCCH candidates to be monitored by the WTRU in the slot, wherein eachof the one or more search spaces is associated with a respective controlresource set (CORESET), and the maximum number of PDCCH candidates to bemonitored by the WTRU in the slot depends on a subcarrier size (SCS);and a receiver configured to receive a wireless signal in the slot;wherein the processor is configured to decode at least one PDCCHtransmission, wherein the PDCCH transmission corresponds to at least oneof the PDCCH candidates, and wherein the PDCCH transmission is comprisedin one or more control channel elements (CCEs) comprised in the wirelesssignal.
 14. The WTRU of claim 13, wherein the processor is furtherconfigured to drop at least one PDCCH candidate from the PDCCHcandidates associated with the one or more search spaces based on anumber of PDCCH candidates associated with the one or more search spacesexceeding the maximum number of PDCCH candidates to be monitored by theWTRU in the slot.
 15. The WTRU of claim 14, wherein the processor isconfigured to drop the at least one PDCCH candidate based on a type ofat least one of the one or more search spaces.
 16. The WTRU of claim 14,wherein at least one of the one or more search spaces is configured suchthat PDCCH candidates associated with the at least one of the one moresearch spaces are restricted to a subset of aggregation levels.
 17. TheWTRU of claim 14, wherein each of the one or more search spaces isassociated with a configured monitoring periodicity.
 18. The WTRU ofclaim 13, wherein the processor is further configured to drop at leastone PDCCH candidate from the PDCCH candidates associated with the one ormore search spaces based on a number of channel estimates to beperformed on CCEs of the PDCCH candidates associated with the one ormore search spaces exceeding a maximum value of channel estimates. 19.The WTRU of claim 18, wherein the WTRU is configured with a respectivenumber of PDCCH candidates per search space for each of the one or moresearch spaces; and wherein the processor is further configured to: scalea number of PDCCH candidates in at least one of the one or more searchspaces based on a total number of configured PDCCH candidates in theslot for all of the one or more search spaces exceeding the maximumnumber of PDCCH candidates to be monitored by the WTRU in the slot. 20.The WTRU of claim 19, wherein the processor is configured to drop all ofthe PDCCH candidates in the slot for the at least one of the one or moresearch spaces to scale the number of PDCCH candidates in the at leastone of the one or more search spaces.